An Application of the LCZ Approach in Surface Urban Heat Island Mapping in Sofia, Bulgaria

This article presents the results of the thermal survey of the capital of Bulgaria (Sofia) carried out in August 2019, with the application of an unmanned aerial system (UAS). The study is based on the concept of local climate zones (LCZs), taking into account the influence of the features of land use/land cover and urban morphology on the urban climate. The basic spatial units used in the study are presented in the form of a regular grid consisting of 3299 cells with sides of 250 ´ 250 m. A total of 13 types of LCZs were identified, of which LCZs 6, 5, 8, 4, D, and A form the largest share. In the thermal imaging of the surface, a stratified sampling scheme was applied, which allowed us to select 74 cells, which are interpreted as representative of all cells belonging to the corresponding LCZ in the urban space. The performed statistical analysis of the thermal data allowed us to identify both the most thermally loaded zones (LCZs 9, 4, and 5) and the cells forming Urban Cool Islands (mainly in LCZs D and C). The average surface temperature in Sofia during the study period (in the time interval between 8:00 PM and 10:00 PM) was estimated at 20.9 °C, and between the different zones it varied in the range 17.2–25.1 °C. The highest maximum values of LST (27.9–30.6 °C) were registered in LCZ 4 and LCZ 5. The relation between the spatial structure of the urban thermal patterns and urban surface characteristics was also analyzed. Regression analysis confirmed the hypothesis that as the proportion of green areas increases, surface temperatures decrease, and, vice versa, as the proportion of built-up and impermeable areas increases, surface temperatures increase. A heat load map (via applying a z-transformation to standardize the temperature values), a map of the average surface temperature, and a map of the average intensity of the heat island on the surface were generated in the GIS environment. The results of the study adequately reflect the complex spatial model of the studied phenomenon, which gives grounds to conclude that the research approach used is applicable to similar studies in other cities.

On the strongly negative cloud feedback over the satellite period implied by observational SST reconstructions

<p>Clouds strongly modulate Earth's radiative budget, and uncertainties in numerical model simulations of the global cloud field contribute substantially to uncertainties in future warming. In coupled atmosphere-ocean General Circulation Model (GCM) simulations, the global cloud field and its radiative effect are well correlated with global average surface temperature. However, GCM simulations with prescribed Sea Surface Temperatures (SSTs) from observational SST reconstructions over the historical period show time-varying relationships between the cloud field and average surface temperature (known as the "pattern effect"). We show that CERES/EBAF observational data confirms the presence of a second mode (in addition to mean SST) in particular in low cloud amount (and correspondingly SWCRE) that is consistent with variations in tropical atmospheric stability in ERA-Interim reanalysis data. This second mode in observations is tied to ENSO, and evolves in quadrature to ENSO indexes. It arises from differences in surface temperature change between regions of tropical deep convection and the tropical (or global) average. In contrast to the multidecadal trends over the full historical period, trends in this second mode since the year 2000 are small. The PCMDI/AMIPII SSTs recommended for CMIP6 stand out as having the largest trend over the full historical period. Different SST reconstructions agree on a trend over the satellite period - specifically the 1980s-90s - that is much larger than what coupled GCM simulations show: In forced coupled GCM simulations the regions of deep convection warm order 10% more than the tropical average, whereas over the satellite period the amplification is order +50%  in the AMIP simulations and in estimates using rainfall observations to identify regions of deep convection.</p>

ANTENNA UNIT HEAT MODE

The article describes the procedure for calculating the thermal regime of a unit. The unit under study is part of a phased array. The calculation of the thermal regime allows you to verify the operability of the device under a steady thermal regime and to verify that the choice of the method of cooling the structure is correct. The work of the unit is analyzed under conditions of convective heat exchange without forced cooling at the maximum operating (permissible) ambient temperature. The calculation of the thermal regime of the unit is carried out in two stages. At the first stage, the temperature of the unit case is determined when the unit case overheats in the first approximation. The overheating value is determined from the graph. The calculation is carried out under conditions of natural air cooling. At the second stage, the average surface temperature of the heated zone is determined. The greatest heating in the unit is observed in the area occupied by the board with ERE. According to the results of the calculation, a problem was revealed, which consists in the fact that under the given operating conditions of the investigated device, the unit area is heated above the maximum operating temperature of some ERE. The value of the average surface temperature of the heated zone of the unit exceeds the value of the maximum allowable temperature of the least heat-resistant element of the heated zone. This means that it is necessary to use forced air cooling by air convection. The article proposes a solution to the problem of unit overheating, and describes the method of forced air cooling and its design.

An Analysis of Various Cooling Liquids in a Two-Cylinder Single-Stage Piston Hybrid Power Machine with Fluid Flow Due to Vacuum at Suction Based on Experimental Results

This paper examines the use of various types of cooling liquids in a two-cylinder single-stage piston hybrid power machine with fluid flow due to vacuum at suction. Liquids with various basic thermal properties were used as working fluids: distilled water, antifreeze, and transmission oil. Specific heat capacities and dynamic viscosities of these liquids differed from 2 to 10 times. The experimental studies showed that the greatest cooling effect on the cylinder-piston group was observed when using distilled water, and the least — when using transmission oil. The average surface temperature of the working chamber when cooled with water was minimal in the range of 330–340 K. The average surface temperature of the working chamber when cooled with transmission oil was maximum and ranged from 345 to 355 K, i. e. it was about 15 K higher than when cooled with water. The average surface temperature of the working chamber when cooled with antifreeze occupied an intermediate position between the average temperatures of the working chamber when cooled with water and that with transmission oil and was in the range of 335–345 K, i. e. about 5 K higher than when cooled with water.

Development of Simulation Tool for Ground Source Heat Pump Systems Influenced by Ground Surface

The authors developed a ground heat exchanger (GHE) calculation model influenced by the ground surface by applying the superposition theorem. Furthermore, a simulation tool for ground source heat pump (GSHP) systems affected by ground surface was developed by combining the GHE calculation model with the simulation tool for GSHP systems that the authors previously developed. In this paper, the outlines of GHE calculation model is explained. Next, in order to validate the calculation precision of the tool, a thermal response test (TRT) was carried out using a borehole GHE with a length of 30 m and the outlet temperature of the GHE calculated using the tool was compared to the measured one. The relative error between the temperatures of the heat carrier fluid in the GHE obtained by measurement and calculation was 3.3% and this result indicated that the tool can reproduce the measurement with acceptable precision. In addition, the authors assumed that the GSHP system was installed in residential houses and predicted the performances of GSHP systems using the GHEs with different lengths and numbers, but the same total length. The result showed that the average surface temperature of GHE with a length of 10 m becomes approximately 2 °C higher than the average surface temperature of a GHE with a length of 100 m in August.

Comparison of surface temperature over different natural and artificial urban surfaces

<p>It is a well-known fact that in urban areas, human activities result in special climatic conditions. Urban climate studies nowadays are becoming more and more important as their results can be directly used by urban planners, architects and municipal decision-makers. In the framework of a long-term cooperation between the Urban Climate Research Group of the Department of Meteorology at the Eötvös Loránd University (Budapest) and the Department of Environment at the Municipality of Újbuda (district XI of Budapest), regular urban climate measurements are carried out in the district XI of Budapest to detect the urban heat island (UHI) effect on different spatial scales.</p><p>Measuring campaigns were conducted in summer 2018 and later, in spring, summer and autumn 2019 to determine the surface temperature of various urban materials using a Voltcraft IR-280 infrared thermometer. The purpose of these measurements was to obtain information about the thermal properties of different urban surfaces, objects in order to analyse which surfaces are suitable for decreasing and hence mitigating the UHI effect. The impact of the colour of different surfaces and the role of shading are analysed as well. The measurements were carried out at two measuring sites: (i) in the largest public park of the district, called Bikás Park (with 37 measuring points), (ii) in the commercial and public transportation centre of the district, called Móricz Zsigmond Square (with 17 measuring points). Based on the compiled database, a detailed statistical analysis was performed to investigate the thermal properties of various urban surfaces, e.g. pavements, walls, street furniture, sport facilities, water and plant surfaces.</p><p>The results show that the coolest surfaces are natural covers (water, vegetation), while the hottest surfaces are concrete pavements, asphalt and rubber paving when exposed to direct solar radiation. In summer, extremely high surface temperatures can occur, the average surface temperature around noon exceeds 40 °C in the case of dark painted wood objects, asphalt and rubber-paved surfaces with sunny conditions. The analysis focusing on the concrete paving blocks with different colours shows that the average surface temperature of light grey surfaces is 5-7 °C lower than the average temperature of darker colours. During the measurement series, the highest temperatures (over 50 °C) were measured at rubber paving-covered sport facilities and playgrounds, in sunny conditions. This material is very popular because its use has many benefits. Our study shows that the extensive use of these surfaces has a negative impact on the urban climate. These surfaces warm up so much during sunny summer days that the facilities covered with this material become practically unusable due to their extremely hot surface. In the case of this surface material, shading plays an important role as it can effectively control and reduce the warming of rubber paving-covered surfaces.</p>

Temperature-related disasters in Europe – a cross-sectional analysis of the emergency events database from a pediatric perspective

This study investigates patterns of extreme temperature-related events in Europe and its significance for the public health, with a focus on the vulnerable pediatric population. A generalized additive model of average surface temperature development for the European countries is described and discussed with an in-depth analysis of the influence of temperature on evolutional and behavioral aspects.MethodsExtreme temperature related events are recorded in the publicly available epidemiological database of Emergency Events (EM-DAT). A comparative and descriptive statistical analysis of this data was conducted with a focus on (prospective) records from 1988 onwards. Average surface temperature data was provided by the World Bank’s Climate Change Knowledge Portal. The criteria for strengthening the reporting of observational studies in epidemiology (STROBE) were respected.ResultsWithin EM-DAT, extreme temperature-related disasters in Europe were categorized as either heat waves, drought, forest or land fires, or cold waves and severe winter conditions, accordingly. The most frequent type of event recorded were cold waves (36.2%). However, cold waves and severe winter conditions only accounted for about 6,460 casualties (4.4%), while heat waves were responsible for a total of 137,533 casualties (95.1%). During the prospective observational period of the EM-DAT database, heat waves in 2003, 2006, 2010, and 2015, claimed a total of 119,760 casualties. These most severe heatwaves were geographically distributed over Russia (2010), as well as France, Italy, Spain, and Germany, each in 2003. Accordingly, analysis of temperature data revealed an increasing average surface temperature for all assessed European countries, correlating with in an increasing frequency of extreme temperature-related events.ConclusionThis study shows that according to EM-DAT data extreme temperatures are an increasingly important public health threat to the European population as the average European surface temperatures are rising. Although cold waves are more frequently reported in EM-DAT, heat waves are the major cause for temperature-related casualties. Therefore, we conclude that evolutional and cultural resilience against cold and drought is significantly higher than it is against heat. Our results project that the frequency, duration and intensity of heat waves will further increase due to current climatic changes and become a more prevalent problem for future generations. Hence, we propose an emergency plan to inform the public and authorities about measurements to be taken in such extreme heat conditions to overcome the prevailing lack of information available to the public.

Study of environmental thermal variation in vineyards harvested by different curtain colors used as lateral closure

The objective of this research was to evaluate the thermal influence of the white and blue colors of the sanitary curtain used as lateral closures in commercial broiler chickens, aiming at the welfare and environment suitable for the production of broilers. At the end of 42 days, the white curtain represented the best average surface temperature, between 27.4º and 35.5º, when evaluated without supplementary ventilation. It was also possible to conclude that the white color curtain was more efficient to maintain the well-being inside the aviary, especially in the sixth week of production, verified by infrared thermography.

Assessing the efficiency of green roof technology: A case study of Masjid Kota Iskandar, Nusajaya, Johor

Green roof is a system that had been identified as a medium that is able to reduce the thermal temperature of a building. It is an efficient way of reducing heat especially for hot climate countries like Malaysia. This study was conducted to assess the ability and the effectiveness of green roof in controlling the temperature of a building and also to make a comparison of its performance with the conventional roof. The study was conducted at the Masjid Kota Iskandar, Nusajaya, Johor. For this case study, Infrared Thermometer and 4 in 1 Meter Kit were used to record the temperature (maximum and minimum) during the day on the surface of the green roof and conventional roof as well as its relative humidity. The experiments were conducted during sunny days from 8.00 am to 6.00 pm at an interval of two hours on two different dates which were 18th March 2017 and 4th April 2017. Few locations for the data to be collected were plotted on the surface of both roofs and the readings of maximum and minimum surface roof temperatures were recorded for comparison. Based on the research that had been carried out, it can be concluded that the usage of green roof was able to reduce the average surface temperature in the range of 3.6°C –11.1°C as compared to the conventional roof. This result had proven that there was a decrease in temperature for the green roof as compared to the conventional roof. It had shown that the usage of the green roof in a building was an efficient way of reducing building temperature and also an effective way to achieve sustainability in architecture and engineering design.

Evaluation of synchronizer loading parameters and their ability to predict failure

Molybdenum coated gearbox synchronizers are tested in a μ-comp test rig under varying loading conditions until failure. Four different parameters used to describe the thermomechanical load are evaluated just before failure to compare their ability to predict failure. The parameters evaluated are the synchronized kinetic energy, the synchronization power, and the focal as well as the average surface temperature increase. The focal surface temperature increase as well as the average surface temperature increase is found to predict failure with relatively good accuracy. It is shown that there exists a threshold which divides the synchronizer into either a very long or a very short service life. Additionally, a method to determine the average surface temperature in the gearbox management system is proposed.